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FAQ # 6

Red Light Camera Studies:
Alternatives to Cameras
(Engineering Countermeasures)


Updated 1-8-12


Question:  Engineers who have studied red light running - those who do not stand to gain financially from the use of red light cameras - suggest that cities try alternatives to cameras before installing cameras.  Why is that, and what are the alternatives?

Part (A) of Answer:  One alternative is to lengthen the yellow light, which is known to dramatically reduce the number of cars running the lights.  One study - details below - showed a 69% decrease in violations when a yellow was increased from 4.0 seconds, to 4.5 seconds.  Other studies - details below - gave similar results, and also rated engineering countermeasures such as longer yellows "most effective" in reducing unintentional running while enforcement, including cameras, was considered "less effective."

Follow-up Question # 1:  What about "rebound?" Won't drivers get used to the longer yellows, and resume running the light?

Answer to Follow-up # 1:  No, drivers do not adjust, and the violations stay down, do not rebound.  Numerous sources confirm that.  Here are some -

a.  One real world example comes from Fairfax County, Virginia.  This graph shows the 69% decrease noted above, and that the effect was long-term, with no rebound in the number of violations.

b.  Another real world example comes from Mesa, Arizona.  Mesa increased left-turn yellows from three seconds to four seconds at six photo enforced intersections, saw an immediate 2/3 (or more) drop in the number of violators at each intersection - which stayed down with no rebound - in the 4+ years after the change.  See the before-and-after figures in the big table at: City of Mesa Documents.

c.  More examples of no rebound after an increase in the length of the yellow:
Atlantic/Telegraph in City of Commerce
Redlands
Mission/Mojave in Fremont
Willow/Bayfront in Menlo Park
Loma Linda
d.   See also the discussion of this question, by traffic engineers, in the Electronic National Dialog on Transportation Operations, at:  http://www.ntoctalks.com/opdialog/index.cgi?read=381 .  The following is a portion of that discussion.

"Research has consistently shown that drivers do not, in fact, adapt to the length of the yellow." [Determining Vehicle Change Intervals - A Proposed Recommended Practice", ITE, 1985]

"Olson and Rothery reported in 1972 that their research showed that drivers were 'virtually' certain to stop if their required deceleration rate was less than 8 feet per second squared [ 0.25 G ] and virtually certain to continue if the deceleration rate required was in excess of 12 feet per second squared [ 0.38 G ]." [Determining Vehicle Change Intervals - A Proposed Recommended Practice", ITE, 1985]

Follow-up Question # 2:  OK, running goes down (and stays down, no rebound) when you lengthen the yellow, but do accidents also go down?

Answer to Follow-up # 2:  Lengthening the yellow also reduces severe accidents.  One source is a 2004 study by the Texas Transportation Institute which found (at page 2-20, see graph below), "…an increase in the yellow duration of 1.0 second is associated with an MF [crash frequency] of about 0.6, which corresponds to a 40 percent reduction in crashes."



Another source is more from the Electronic National Dialog:  "The average implied deceleration rate of the group with the highest crash rate was slightly over 13 feet per second squared [ 0.41 G ], and the deceleration rate for the group with the lowest crash rate was 8.5 feet per second squared [ 0.27 G ]." ["Effect of Clearance Interval Timing on Traffic Flow and Crashes at Signalized Intersections," Zador/Stein/Shapiro/Tarnoff, ITE Journal, November 1985]


Part (B) of Answer:  Another alternative is to improve street markings.  2005 research sponsored by the Florida Department of Transportation concluded that improving street markings (plain old paint!) near intersections would reduce red light running by up to 74 percent.  (Section 3.4, p. 69 of the document, or p. 84 of the pdf.)  A large red light camera study sponsored by the San Diego Police Department rated engineering countermeasures such as better markings as "most effective" in reducing unintentional running whereas enforcement, including cameras, was considered "less effective."  (Table 6.3, p. 80 of the document, or p. 97 of the pdf.)

A couple more engineering countermeasures are larger signal lamps (12" dia. instead of 8"), adding backboards to the signals and, where there is no signal light on the "near side" of the intersection, adding one.  highwayrobbery.net suggests that cities should put up large lighted name signs, including for the smaller cross streets.  

Adding these cues becomes even more important when the intersection is missing much of the urban junk - gas stations, crossing overhead utility lines, commercial signage, bus benches - that usually demarks signalized intersections in an urban area. 

Culver at Farwell, Irvine, CA, from Google Maps
Culver at Farwell in Irvine, Site of Jan. 2011 Fatal Crash

There's no denying that a clean spare look, like this intersection in Irvine, is attractive, but if you don't have the urban junk you need to add  other visual cues.

Visual cues are also important where there's too much urban junk competing for drivers' attention, as at the two intersections pictured below.

Linden NJ camera equipped intersectionImpending crash at St. Georges/Stiles, Linden, NJ, site of an ATS camera
(White arrows point to signals, which are yellow.  The driver turning left was found to be at fault.  See discussion on the Industry PR page.)


Reseda Bl. at Busway, LA, CA
Reseda Blvd. at the Busway, in the San Fernando Valley, site of a camera operated by the Metro/MTA


Do Cities Deliberately Avoid Using These Countermeasures?

Internal documents from the City of San Diego show numerous intersections rejected as camera sites, with the notation, "long yellow - vio(lation) volume not there" - an Industry acknowledgment that at intersections with longer yellows, there will not be enough violations to make the system pay.

If you want to find out if the City studied or applied countermeasures at the intersection where you were ticketed, ask them about it, via a public records request.


Conclusion

Most people who intentionally run signals do so by just a small fraction of a second.  On the other hand, a search through the accident photos (captured by ticket cameras) that the Industry has posted on the 'net yields, almost exclusively, photos of accidents which occurred multiple seconds after the light turned red - accidents that most likely were caused by unintentional running.  (Who would deliberately run a signal by the ten or twenty seconds shown on many of the Industry's photos?)  The preponderance of photos with long red times among the Industry's crash photos argues that unintentional running is more dangerous than intentional running.  Engineering countermeasures such as longer yellows and better markings are more effective against unintentional running than is enforcement.

Among the advantages of doing the alternatives above (engineering countermeasures) are -

(1)  A reduction of red light running by ALL drivers, including visitors to town and unintentional runners - not just the "locals" who know that there are cameras around.

(2)  A statistically significant decrease in the number of severe accidents without a "side-effect" increase in rear-end accidents.  (For more about rear-enders, see FAQ # 19.)

(3)  These alternatives are cheap, so can be done on all problematic intersections in town, not just a few.

(4)  Fixing the problematic intersections - rather than maintaining the status quo and taking pictures of the carnage - helps to protect the city against liability claims arising from accidents.


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